whenever

Shorthand for watching a signal to be true.

Usage

use leptos::prelude::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (is_ready, set_ready) = signal(false);

whenever(move || is_ready.get(), |v, _, _| log!("{}", v));

    view! { }
}

Callback Function

Same as fn@crate::watch, the callback will be called with callback(input, prev_input, prev_return).

use leptos::prelude::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (is_ready, set_ready) = signal(false);
whenever(move || is_ready.get(), |value, prev_value, _| {
    log!("before: {prev_value:?}; now: {value}");
});

    view! { }
}

Computed

Same as fn@crate::watch, you can pass a getter function to calculate on each change.

use leptos::prelude::*;
use leptos::logging::log;
use leptos_use::whenever;

pub fn Demo() -> impl IntoView {
let (counter, set_counter) = signal(0);
whenever(
    move || counter.get() == 7,
    |_, _, _| log!("counter is 7 now!"),
);

    view! { }
}

Options

Options and defaults are same as fn@watch_with_options.

use leptos::prelude::*;
use leptos::logging::log;
use leptos_use::{WatchOptions, whenever_with_options};

pub fn Demo() -> impl IntoView {
let (counter, set_counter) = signal(0);
whenever_with_options(
    move || counter.get() == 7,
    |_, _, _| log!("counter is 7 now!"),
    WatchOptions::default().immediate(true),
);

    view! { }
}

Server-Side Rendering

On the server this works just fine except if you throttle or debounce in which case the callback will never be called except if you set immediate to true in which case the callback will be called exactly once.

Feature

This function is only available if the crate feature whenever is enabled

Source

Source • Docs